Process for the production of highindene-content hydrocarbon oils



Patented Apr. 14, 1942 PROCESS FOR. THE PRODUCTION OF HIGH- INDENE-CONTENT HYDBOCABBON OILS Karl H. Engel, West Englewood, N. J.,' assignor,

by mesne assignments, to Allied Chemical 8; v

Dye Corporation,

a corporation of New York Application May 15, 1940, Serial No. 335,330

13 Claims. I

This invention relates to the production and purification of indene-containing oils and more particularly to the production of hydrocarbon oils of a high indene content from hydrocarbon oils of relatively low indene content.

Indene has heretofore been recovered from crude indene-containing hydrocarbon oils by containing hydrocarbon oils by carefully fractionatingthe oils to obtain a fraction having an indene content of about 80% and then cooling the fraction to temperatures of about C. to cause the indene to freeze and separate from the oils. Fractionation of indene-containing hydrocarbon oils by the usual distillation methods, no matter how carefully conducted, fails to produce oils of an indene content substantially higher than 80-81% for the reason that many of the oils contained in crude indene-containing hydrocarbon oils have practically the same boiling point as indene itself and cannot be separated therefrom by ordinary fractionation. None of the above methods of obtaining indene have been found to be commercially satisfactory from an economic viewpoint.

It is an object of this invention to provide a simple and inexpensive method of obtaining oils of high indene content from oils of relatively low indene content, Other objects of this invention I will appear from the following detailed description. Y

This application is directed to a species of the generic invention disclosed and'claimed in my copending application Serial No. 335,331 filed on the same day as the present application. My copending application Serial No. 335,329, filed on the same day as the present application, is directed to another species of the generic invention disclosed and claimed in application Serial No. 335,331. The species to which the present application is directed involves the distillation of hydrocarbon oils of relatively low indene content in the presence of a glycol compound capable of forming azeotropes with indene and the nonindene oils contained in the hydrocarbon oil. By the term glycol compound I intend to include both glycols and g'lycol ethers. Glycol compounds boiling from about 145 C. to about 220 C. have been found eminently satisfactory in practicing this invention. I have found the glycol compound, on addition to a hydrocarbon oil of relatively low indene content, forms with the constituents of the oil azeotropes of the minimumboiling type; i. e., they distill at temperatures lower than the distillation temperatures of any of the azeotrope constituents. Furthermore, I have found that the azeotropes formed with the non-indene oils contained in a fraction from which relatively high-boiling constituents have been previously removed have substantially lower distillation temperatures than the distillation temperatures of indene and of the indene-glycolcompound azeotropes, so that on fractional distillation the-non-indene oils are distilled off as azeotropic mixtures with the glycol compound, leaving in the still a hydrocarbon oil of high indene content.

The glycol compounds have been found to be particularly advantageous for use in accordance with this invention, for in addition to their property of forming azeotropes with indene and the non-indene oils, they are immiscible with the hydrocarbon oils at room temperatures (about 22 C.) so that they may be separated from the distillate by cooling and subsequent decantation.

This property of the glycol compounds makes it possible to conduct the separation of indene and non-indene oils according to-this invention with the use of only small amounts of glycol compound. for as fast as thesglycol compound separates on cooling from the distillate it may be Y continuously returned to the hydorcarbon oil being distilled for reuse.

Indene-containing hydrocarbon oils, as is well. known, maybe obtained by fractional distillation of coal tar oils, drip oils, carburetted water-gas tar oils, oil-gas-tar oils, and light .oils recovered in coal gas and water-gas operations. In accordance with this invention the indene-containing hydrocarbon oils are mixed with a glycol compound so as to form azeotropes with indene and the non-indene oils and the mixture is fractionally distilled to effect the separation of the non-indene azeotropes from the indene. Since the glycol compounds form minimum-boiling azeotropes with the non-indene oils, it has been found desirable before the addition of the glycol compound to subject the indene-containing hydrocarbon oils to be treated according to this invention to ordinary fractional distillation in order to remove non-indene oils of substantially different boiling range from indene, particularly those of substantially higher boiling range than indene. The removal of these oils reduces the amount of glycol compound required for the distillation, minimizes contamination of the highindene-content product by azeotropes formed of the glycol compound and higher boiling nonindene oils, and increases the yield of indene by reducing the volume of material which must be distilled, thus lessening the amount of indene carried into the distillate.

The particular method of carrying out the distillation may vary without departing from the scope of my invention. Atmospheric pressure or pressures below atmospheric may be used; utilization of pressures below atmospheric permit greater economy of heat without affecting the efficiency of the separation of indene and nonindene oils. It should be'noted, however, the ratio of hydrocarbon oil to glycol compound in the azeotrope may change slightly at reduced pressures, generally increasing. The entire amount of glycol compound necessary to complete the fractionation maybe added to the indene-containing hydrocarbon oil before fractionation, in which case suflicient glycol compound should be added to the oil so that the azeotropic ratio of glycol compound to non-indene oils in the distillate will, be maintained throughout the fractionation. The glycol compound may be added intermittently to the fractionating column as the distillation proceeds in amounts sufficient to maintain the desired azeotropic ratio in the fractionating column. Because of the immiscibility of the glycol compounds with hydrocarbon oils at room temperatures, these compounds may be separated from the hydrocarbon oils distilled from the column by cooling the distillate to room temperature and separating the glycol compound layer from the hydrocarbon oil; the glycol compound thus separated may then be returned directly to the fractionating column, preferably to the bottom thereof, and reused. In this way the proper azeotropic ratio of glycol compound to hydrocarbon oils in the fractionating column may be maintained with the use of a minimum amount of glycol compound, so that a large quantity of the glycol compound does not have to be kept in storage for use in the fractionation.

At the beginning of the fractionation the distillate consists almost entirely of the azeotropic mixture of glycol compound and the non-indene oils, but as fractionation proceeds and the temperature approaches the distillationtemperature of the glycol-compound-indene azeotrope, the

indene content of the distillate gradually increases. The course of fractionation may be followed by taking samples of the distillate and testing them for their indene content. The point at which fractionation is discontinued depends I upon the indene content of the hydrocarbon oil being treated, upon the desired indene content of the final product, and upon the efficiency of the glycol compound used in separating the indene and non-indene oils. Thus, the lower the indene content of the hydrocarbon oil being treated and the higher the desired indene content of the final product, the longer fractionation of the oil must be continued; while the higher the separationefficiency of the glycol compound, the shorter will be the time necessary to obtain a hydrocarbon oil of the desired indene content. Obviously, the longer fractionation is continued, the smaller will be the'yield of the desired highindene-content hydrocarbon oil. If desired, fractionation may be continued until substantially the entire indene content of the charge has been distilled, thereby recovering from the last distillate cut an oil containing about 98% indene. Fractionation of the mixture, however, is ordinarily discontinued when the indene content of the distillate shows the still residue contains from 90% to 95% indene (exclusive of the gly'col compound, if any) and the still residue is then distilledstraight, i. e. without fractionation, obtaining thereby the desired highindene-content hydrocarbon oil.

The distillate recovered during the course of the fractionation contains substantially all of the glycol compound added to the indene-containing oil and also varying amounts of indene, in addition to the non-indene oils. The distillate is allowed to cool, whereby the glycol compound separates practically quantitatively from the hydrocarbon oil. The glycol compound thus recovered is preferably returned to the still for reuse. The distillate oil fractions which contain appreciable quantities of indene may then be recycled by the above-described process to recover the indene content therein; or it may be treated in the ordinary manner with sulfuric acid to poly-' merize the indene and obtain hydrocarbon oils for solvent purposes and the like.

' As examples of the glycol compounds suitable for use in accordance with this invention, the following may be mentioned: ethylene glycol, propylene glycol, and diethylne glycol monomethyl ether. It will be noted these compounds are liquid at the temperature at which distillation is carried out and miscible at such temperatures with the indene-containing oils to be treated. It will further be noted that these compounds all boil within the preferred range of about 145 C. to about 220 C., ethylene glycol boiling at 197 C., propylene glycol at 187.4 C.

and diethylene glycol mono-methyl ether at 193.2 C. Of 'these compounds, propylene glycol has been found to be the most effective from the standpoint of its eficiency in separating the indene and non-indene azeotropes. However, ethylene glycol is preferably used, as its efiiciency is almost as high as propylene glycol and its cost is substantially less.

The following examples are illustrative of the practice of this invention. Amounts are given in parts by volume. The indene percentages were calculated from the relation of the specific gravity of the oil to that of a similar oil of known indene content.

The accompanying drawing is a flow diagram illustrating a preferred method of carrying out the process of my invention.

Reference numeral I indicates an azeotropic fractional distillation operation in which a mixture of a glycol compound and a close-cut indene fraction, e. g. a drip oil high-flash naphtha fraction of boiling range 176-183 0., enter the process as indicated at 2 and are subjected to azeotropic distillation. As above'indicated the overhead product consists primarily of an azeotrope of glycol compound and non-indene components of the oil. This mixture is cooled to room temperature as indicated at .3, whereupon the glycol compound separates; the separated glycol compound may be returned to the azeotropic fractionation step as indicated at 4. The low indene oil from which the glycol compound has been separated is withdrawn as indicated at 5. This oil may contain appreciable quantities of indene and may, therefore, be refractionated, with the use of glycol compound or other azeotropic agent if desired, to recover indene contained therein.

The high indene oil withdrawn as residue from the azeotropic fractionation may contain tracesof glycol compound; as above indicated, traces of glycol compound may be removed by washing the oil with water. The high indene'oil is then subjected to distillation as indicated at 6 to produce an indene distillate which may contain up to about 98% indene. The high boiling residue which contains some indene may be treated to recover the indene contained therein. The in-' be separated by filtration as indicated'at 8. The

filtrate from this operation may be reworked to recover indene contained therein.

Example 1.--500 parts of a drip oil high-flash naphtha fraction boiling from 176 to 183 0., having a specific gravity of 0.948 at22 C. and an indene content of 70% were mixed with 110 parts of ethylene glycol,-and the mixture was fractionally distilled in a 32-ba1l 7-foot column. The glycol separated from the distillate hydrocarbon oil when cooled to 22. C. Distillate cuts of 70 parts each were tested by permitting the glycol to separate from the distillate oil, washing the oil with water to remove traces of glycol, drying, and then determining the specific gravity of the oil. The following table shows the results of these tests:

Ratio distillate oil/glycol Indene in distillate oil Sp. 2!. of distillate oil at 22 0.

Parts of distillate Percent Fractional distillation was discontinued after 420 parts of distillate had been recovered and the still residue was then distilled straight, yielding, after separation of the glycol contained therein, 187 parts of a hydrocarbon oil of specific gravity at 22 C. of 0.977 and in indene content of 91.5%.

Example 2..500 parts'of a drip oil high-flash naphtha fraction boiling from 176 to 183 C., with a specific gravity of 0.948 at 22 C. and .an indene content of 70%, were mixed with 110 parts of propylene glycol, and the mixture was then fractionally distilled in a 32-ball 7-foot column. The glycol separated from the distillate oil when cooled to 22 C. Distillate cuts of 70 parts each were tested by permitting the glycol to separate from the distillate oil, washing the oil with water to remove traces of glycol, drying, and then determining the specific gravity of the oil.

The following table shows the results ofthese tests: 4

, Ratio dis- Sp. gr. of indene in Parts of distillate g tillate distillate oil distillate oil/glycol at 22 C. oil

Percent Fractionation was discontinued after 420, parts of distillate had been recovered and the still residue was then distilled straight, yielding, after separation of the small amount of glycol contained therein, 180'parts of a hydrocarbon oil of specific gravity at 22 C. of 0.982 and containing 95% indene. By combining the last cut, i. e. the cut from 350-420 parts, with the straight distillate and separating glycol therefrom, 225 parts of a hydrocarbon oil containing 93.5% indene were obtained l Example 3.-500 parts of a drip oil high-flash naphtha fraction boiling from 176 to 183 C., having a specific gravity of 0.948 at 22 C. and an indene content of were mixed with 100 parts of diethylene glycol mono-methyl ether and the mixture was then fractionally distilled in a 32- ball 7-foot column. The glycol ether separated from the hydrocarbon oil in the distillate'when cooled to 22 C. Distillate cuts of 70 parts each were tested by permitting the glycol ether to sep arate from the hydrocarbon oil, washing the oil with water to remove traces of the glycol ether,

' of these tests:

Indene in distillate oil Column Parts of distillate ,1 temp.

O. Percent Moisture Fractionation was discontinued after 420 parts of distillate had been recovered and the still residue was then distilled straight, yielding, after separation of the small amount of glycol ether contained therein, 156 parts of a hydrocarbon 011 having a specific gravity of 0.980 at 22 C. and containing 92% indene.

Example 4.16,450 parts of drip oil high-flash naphtha boiling from 176 to 183 6., having a specific gravity of 0.937 at 15.5" C. and an indene content of 54% were mixed with 1,000 parts of propylene glycol and the mixture fractionated in a packed column. The distillate was condensed and permitted to separate into two layers, the lower propylene glycol layer being continuously withdrawn and returned to the bottom of the fractionating column for reuse. The hydrocarbon oil layers separated in the condenser were tested periodically, after removal of the small amounts of propylene glycol remaining in the oils, to determine their specific gravity from which their indene contents were calculated. The following table showing the volume of each cut tested gives the results of these tests:

Fractionation was discontinued after 10,965 parts of distillate had been recovered and the still residue was then distilled straight, yielding, after separation of the propylene glycol, 3,480 parts of an oil having a specific gravity of 0.982 at 155 C. and containing 90% indene. The propylene glycol was recovered practically quantitatively, but was slightly contaminated with hydrocarbon oils. It can be reused for further separation of indene and non-indene oils. Thus, for every 100 parts of crude high-flash naphtha containing 54% indene, the distillation yielded about 67 parts of an oil containing 34% indene and about 21 parts of an oil containing 90% indene.

If it is desired to obtain pure indene from the hydrocarbon oils of high indene content produced according to this invention, the oils may be cooled to from about -l C. to about C. and the solid indene thus formed separated from the oil.

From the above description it will be evident this invention provides a simple and inexpensive method of obtaining hydrocarbon oils of a high indene content from hydrocarbon oils of a relatively low indene content.

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon ofl of relatively low indene content, the step which comprises distilling the hydrocarbon oil 01 relatively low indene content in the presence or a glycol compound capable of forming azeotropes with the non-indene oils contained in the hydrocarbon oil.

2. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content having a boiling range in the neighborhood of indene boiling point, the step which comprises distilling the hydrocarbon oil of relatively low indene content in the presence of a glycol capable of forming azeotropes with indene and the non-indene'oils contained in the hydrocarbon oil.

3. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the step which comprises distilling the hydrocarbon oil 01' relatively low indene content in the presence of a glycol ether capable of forming azeotropes with indene and the non-indene oils contained in the hydrocarbon oil.

4. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the step which comprises distilling the hydrocarbon oil of relatively low indene content in the presence oi. an amount of ethylene glycol suflicient to form an azeotrope with non-indene components of the oil.

5. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the step which comprises distilling the hydrocarbon oil of relatively low indene content in the presence of an amount of propylene glycol suflicient to form an azeotrope with non-indene components of the oil.

6. In a method of producing a hydrocarbon oil oi high indene content from a hydrocarbon oil of relatively low indene content, the step which comprises distilling the hydrocarbon oil of relatively low indene content in the presence of an amount of diethylene glycol mono-methyl ether suflicient to form an azeotrope with non-indene components of the oil.

'7. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the steps of adding to the hydrocarbon oil of relatively low indene content obtained by fractional distillation 01' coal tar oils, drip oils, carburetted water-gas tar oils, oil-gas-tar oils and light oils recovered in coal gas and water-gas operations a glycol compound capable of forming azeotropes .with indene and the non-indene oils contained in the hydrocarbon oil, the non-indene azeotropes having lower distillation temperatures than those of indene, the non-indene oils, and the indene azeotrope, fractionally distilling the mixture, recovering the hydrocarbon oil of high indene content from the still residue, cooling the recovered oil to between about 10 and about 20 C.

' recovered in, coal-gas to produce a hydrocarbon mixture of relatively v low indene content having a boiling and separating solidindene-frorn the cooled oil. 8. In a method of-producing a hydrocarbon oilof high indene content from a hydrocarbon oil of relatively low indene content, the step" which comprises distilling the hydrocarbon oil of relatively'low indene content in the presence of boiling point lies be- 1 a glycol compound whose tween about 145? C.-and about 220 C. and which is capable of forming azeotropes with indene and the non-indene oil's contained in the hydrocarbon oil.

9. A method hydrocarbon oil of relatively low indene content having a boiling range'in theneighborhood of indene boiling point, which comprises distilling thehydrocarbon oil of relatively low indene content in the presence of a gly'colicompound capable of forming azeotropes with indene and the non-indene; oils contained in ,the hydrocarbon oil, recovering the hydrocarbon .oil'of high indene content, cooling the hydrocarbon oil thus ,recovered' to cause solidificationof pure indene,

and separating pure'indene fromathe cooled oil.

10. In a method :of. producing a, hydrocarbon oil 01' high indene content, the steps'iwhich comprise fractionally distilling a crude selected from the group coal-tar 0118,; drip oils, carburetted water-gas-tar oils' oil-gas recovered in coal-'gas'and water-gas operations to produce a hydrocarbon mixture ofrelati'vely low indene content having a boiling range in the neighborhood of indene boiling point, addin to the mixture thus produced an amount of ethylene glycol sufficient to form anazeotrope with nonindene components present in the mixture, fractionally distilling the mixture, and recovering the of producing pure indene from a I to the, propylene glycol suiiicient to form an .azeotrope' with non-indene components present in the rnix- Y covering the the neighborhood of indeneboilingfpoint, adding mixture thus produced an amount of ture, fractionally distilling the mixture, and retent from the still residue.

mixture, and recovering water-gas tar tar oils and light oils" hydrocarbon oil'or high indene content from the still residue. r

11. In a method of 'producing a hydrocarbon oil of high indene content, the steps which comprise fractionally distilling. a crude selected from the group coal-tar oils, drip oils, carburetted water-gas tar oils, oil-gas tar oils and light oils and water-gas operations range in 'the sun. r;

I 12. In a method of producing ahydrocarbon oil of high indene content, the steps which com- I prise Iractionally distilling a crude selected from the group coal-tar 'oils', drip oils, 'carburetted water gas tar oils,-oil-gas tar oils and light'oils recovered in'coal-gas' and water-gas operations to produce a hydrocarbon mixture of relatively low indene content having a'boiling range inthe neighborhoodof indene boiling point, adding'to the mixture thus producedqan amount of di-" ethylene glycol mono-methyl ether sufficient to form an azeotrope with non-indene components iractionally the the hydrocarbon oil of present in the mixture,

high indene content from the still residue.

13, In a niethod'of producing a hydrocarbon oil of high indene content, the steps which comrise-fractionally distilling a crude selected from the group coal-tar oils, drip oils carburetted oils, oil-gas'tar oils, and light oils recovered in coal-gas and water-gas operations to produce a hydrocarbon mixture of relatively low indene content having a-boiling range in the neighborhood or indene boiling point, adding to Y the hydrocarbon mixture thus produced a glycol compound capable of forming azeotropeswith indene and the non-indene components contained inthe hydrocarbon mixture, thenondistillation temindeneazeotropes having-lower the non-indene peratures than thoseot indene,

components and the indene azeotropes, fractionally distilling the mixture, recovering the hydrocarbon oil of high indene content from the still residue, cooling the recovered oil to room temperatures, collecting the glycol compound which separates therefrom, and returning it to hydrocarbon oilof high indene con- 7 

